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arXiv · 1203.2519

Probing MHD Shocks with high-J CO observations: W28F

A. Gusdorf·S. Anderl·R. Guesten·J. Stutzki·H-W. Huebers·P. Hartogh·S. Heyminck·Y. Okada
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Abstract

Context. Observing supernova remnants (SNRs) and modelling the shocks they are associated with is the best way to quantify the energy SNRs re-distribute back into the Interstellar Medium (ISM). Aims. We present comparisons of shock models with CO observations in the F knot of the W28 supernova remnant. These comparisons constitute a valuable tool to constrain both the shock characteristics and pre-shock conditions. Methods. New CO observations from the shocked regions with the APEX and SOFIA telescopes are presented and combined. The integrated intensities are compared to the outputs of a grid of models, which were combined from an MHD shock code that calculates the dynamical and chemical structure of these regions, and a radiative transfer module based on the 'large velocity gradient' (LVG) approximation. Results. We base our modelling method on the higher J CO transitions, which unambiguously trace the passage of a shock wave. We provide fits for the blue- and red-lobe components of the observed shocks. We find that only stationary, C-type shock models can reproduce the observed levels of CO emission. Our best models are found for a pre-shock density of 104 cm-3, with the magnetic field strength varying between 45 and 100 μG, and a higher shock velocity for the so-called blue shock (\sim25 km s-1) than for the red one (\sim20 km s-1). Our models also satisfactorily account for the pure rotational H2 emission that is observed with Spitzer.

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A. Gusdorf, S. Anderl, R. Guesten, J. Stutzki, H-W. Huebers, P. Hartogh, S. Heyminck, Y. Okada. 2012-03-12. Probing MHD Shocks with high-J CO observations: W28F. https://doi.org/10.1051/0004-6361%2F201218907

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